From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932655AbdBVOrV (ORCPT ); Wed, 22 Feb 2017 09:47:21 -0500 Received: from mout.gmx.net ([212.227.17.22]:51130 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932726AbdBVOrN (ORCPT ); Wed, 22 Feb 2017 09:47:13 -0500 Message-ID: <1487774800.4487.15.camel@gmx.de> Subject: Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency consideration From: Mike Galbraith To: Alex Shi , Peter Zijlstra Cc: LKML Date: Wed, 22 Feb 2017 15:46:40 +0100 In-Reply-To: References: <1487768197.27533.5.camel@gmx.de> <20170222131218.GS6515@twins.programming.kicks-ass.net> <1487769542.4487.2.camel@gmx.de> Content-Type: text/plain; charset="us-ascii" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K0:hVTztrH6FL5FSMaC5WLU90rab50b2rbOr7bdxoYvbH/OIVoBt1U PlVSzfavjCI217wYRHpmspOM8ZNhqzmYgphg4vS1cw6d1bWkbFtCY+4yHzP8I21ruHkt1ZY HAZ3IH20YCaIu2jejvNoxhIo3mjiRRY39eyp7ULR/ATOmM0LBVX+evMMuH2ZHCrDjkIGQAT +CteQsNhka9I4w1t/hWqw== X-UI-Out-Filterresults: notjunk:1;V01:K0:mLcKtTJbsVo=:q7e0wELqjsPeLZ+m0rB8y6 ePfZBPN65PMvteOXSk5MqZP1O9cL2leZTGoe+1RluEXOT5f8UiyCpKK18Spix4VSQel2mzQ+t 8V/qVjgFMJL1v0VIT4mKffo36B7/nJqrBNCV9diDEbIoJpx+Zktc34GrjxLFev8IEbDNWvcpQ ANnq3G9XilmhJ1+JIILO9Lj5xII8+PdSzIVAmzrzRletRAC58Sq59GWWbvsMq31kZt0RqTMkX MDp1NsCaGyfgP9/V2/NiUpT+K0dmlgudZ487Dk1GXIoIKzbtmFupA24tc4+3KNM1lDAeBpQFf wIkIERe7uFuGcQYlatTNUhLSsScxLaWNNiTSEbY3uKr8YhPPXFjT7JurN4AVqy45lLI+6LhY+ qZdr726fSJmN30SY1y8PbngfakWDHnagwcbSAX49ifVSawKFhUvNeLRbmd0XomenWxGHTHRdy +tHjCHOZ5+7J7DjNlyYSOc0G8YVGBGWqkOlfRNgG42D0HoFNAXADWlUpEs9w1Hs8m/+2COVZI yuzbQ8VjFVU1YHXUpoDd5BghM1+EIarnl/UbKMm++hdkl4WV4dgsuB7xY+BBjOpsbr6SK8xzI OdPKOPDYprnR75FVAhsZNohUnDHI6+DH2hFD1rbi8eQ/UKdxCThQc7+o5y8+6fLv4dSVJ6KJF Bh4OSvPz4FHvLeykoKfb7mU5PNBtbIInrSzhxWawCxw0q89XnTSqkaxSDiQpOWVtKPkj0j+za pLuKMRhcSqm4I9apT79VKlayq7L42DGXlfLRmXFB6Zq1mrQY5psd+3UM2EfcSJ/BFP85xnaVB tz+TrUfuqB025+cdX3TI+b3uIWuZY7za37/Rb939Q8L419KwIZx9DMY+vKaeRXWSSH/HoilNN xd+2IMtPGaYPfaT/6urCj+6hTfcdhhKrA1ctb0sFiJGkknsP1bQTPJBCWWJtIjnxaIaWj40hg /k6u9MJArsKZv1ZWletTSXVOG7VjMKeL+T78DRr2zGDj7lWXhfFVWEkGJG44EBkgDLz5srhw1 h76jIxyBln2KnGjcFNdUJD3HqqrTIAhwQD5icK/RIjEXD2rzcDfBiiVCzpQygMWeig== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2017-02-22 at 22:31 +0800, Alex Shi wrote: > > On 02/22/2017 09:19 PM, Mike Galbraith wrote: > > On Wed, 2017-02-22 at 14:12 +0100, Peter Zijlstra wrote: > > > On Wed, Feb 22, 2017 at 01:56:37PM +0100, Mike Galbraith wrote: > > > > Hi, > > > > > > > > Do we really need a spinlock for that in the idle loop? > > > > > > Urgh, that's broken on RT, you cannot schedule the idle loop. > > > > That's what made me notice the obnoxious little bugger. > > Hi Mike, > > Sorry for this bug. Guess the rt_spin_lock call some function in > rtmutex.c:995. Could you like to show me how to reproduce this bug? Yeah, spinlock_t is transmogrified into an rtmutex in RT trees. No need to reproduce, if you just make the lock go away, RT trees will become happy camper again, and NONRT trees won't have to feed yet another an cycle sucking lock in the fastpath. -Mike